German patent DE 10 2005 003 827 B4 describes a device and a method for interaction between a person and a robot unit at a robot workplace, wherein the approach of a person is monitored with respect to two safety thresholds. A first sensor unit detects that a person is approaching the workplace; the detection is done in such a way that a first signal is generated if a first safety distance is breached, and a second signal is generated if a second safety distance is breached. After the first signal has been triggered, it is provided that the robot unit is switched to a predefinable state, to a so-called safe operating stop. After the second signal has been triggered, the robot unit is switched to a so-called emergency-off state in the which the robot unit remains motionless in its momentary position. It is also provided that an additional safety switch that switches the robot unit to the safe operating stop state is arranged at the workplace of the robot unit.
German patent DE 103 20 343 B4 discloses a method for monitored cooperation between a robot unit and a person in which, according to a predefinable program sequence, handling steps are carried out in a shared workspace that is accessible to the robot unit as well as to the person. Here, it is provided that, as the robot approaches the person, a pattern of movement is communicated to the robot unit, and this pattern is characterized by the direction of movement, the speed of movement as well as the distance of the robot unit with respect to the person. A person-specific pattern of movement is selected from a plurality of different stored patterns of movement, so that the person is given a feeling of safe working conditions as well as of control over the robot unit. Each pattern of movement is present in at least a first quality level and a second quality level that differ from each other, for instance, in terms of their speed of movement and/or direction of movement. Taking into consideration the momentary braking distance of the robot unit as well as the maximum speed of movement of the person, the robot unit is braked or brought to a standstill until there is no longer a risk of collision.
Likewise known from the state of the art are systems for three-dimensional image detection that operate with the aid of active illumination. These include TOF or transit time measuring systems. These systems employ amplitude-modulated or pulsed light for purposes of illuminating the three-dimensional scene that is to be detected.
The terms camera or camera system are meant to encompass all 3D TOF camera systems that acquire transit time information from the phase shift of radiation that has been emitted and received. Suitable 3D TOF cameras are especially photonic mixer device (PMD) cameras having PMD detectors of the type described in German application DE 196 35 932, European patent application EP 1 777 747, U.S. Pat. No. 6,587,186 as well as German patent application DE 197 04 496; these cameras can be obtained from the IFM ELECTRONIC GMBH company under model name FRAME GRABBER O3D101/M01594. In particular, the PMD camera allows a flexible arrangement of the source of light and the detector, which can be installed either in a housing or else separately.